The interaction of α-chymotrypsin with one persistent organic pollutant (dicofol): spectroscope and molecular modeling identification.

Great attention is devoted to persistent organic pollutant (POP), among which the pesticide dicofol is critical related to food safety and might raise the risk of cancer incidence. To take a comprehensive evaluation of its toxicity, we investigated its interaction with a serine protease α-chymotrypsin by multi-spectroscopic techniques and molecular modeling method. UV-vis absorption, synchronous fluorescence, and circular dichroism data elucidated that dicofol unfolded the framework of α-chymotrypsin and led to secondary structure changes. The fluorescence and lifetime assay determined the static quenching mode and binding parameters. As an auxiliary method, molecular modeling has displayed the specific binding site and information about binding forces and drug-residues distances which were consistent with conclusions from above. Additional, enzyme activity assay gave evidence at the functional aspect to clarify the fact that dicofol could contribute to the conformational changes and furthermore alter the function of the enzyme.